In a variety of technologies, there is a continuing need for stronger, corrosion-resistant and wear-resistant materials. For example, research into nickel-based alloys has resulted in the development of alloy additions that display minor but important property improvements. It is believed that still further improvement can be obtained by controlling the microstructure of such alloys. Directionally solidified alloys and single crystal alloys are examples of alloy microstructure control that find application in numerous industries, including the aerospace industry.
In the realm of microstructures, the amorphous-type microstructure has not yet been fully exploited. Amorphous metals, also sometimes referred to as glassy metals or liquid metals, are generally formed by extremely rapid quenching of a specific alloy composition from the liquid state. The rapid cooling process solidifies the liquid structure which has no long range periodicity such that an amorphous, rather than crystalline, microstructure appears in the solid. Amorphous ribbon or foil is routinely produced by casting molten metal on a rotating wheel as described in several US patents, examples of the more recent being U.S. Pat. No. 4,664,176, CASTING IN A THERMALLY-INDUCED LOW DENSITY ATMOSPHERE, and U.S. Pat. No. 5,842,511, CASTING WHEEL HAVING EQUIAXED FINE GRAINED QUENCH SURFACE. These materials are sold under the Metglas® name for use as transformer laminations, braze foil, and security strips. Amorphous or microcrystalline material can also be formed by some powder production routes, such as produce very fine usually spherical powders of about 1 to 30 microns depending upon the alloy. It is therefore known how to manufacture metal alloys in ribbon, wire, and particle type shapes where the alloy possesses the amorphous microstructure. These amorphous metals have displayed promising characteristics, including high strength and corrosion resistance.
The use of amorphous materials, particularly aluminum alloys, titanium alloys, and nickel alloys, in practical industrial applications, has nevertheless been limited. One problem encountered in the use of amorphous materials is that the production of larger, consolidated structures from the starting ribbon or powder forms may require the use of elevated temperature processing. However, that exposure of an amorphous material to elevated temperature often results its crystallization and the loss of the amorphous microstructure. U.S. Pat. No. 4,582,536, PRODUCTION OF INCREASED DUCTILITY IN ARTICLES CONSOLIDATED FROM RAPIDLY SOLIDIFIED ALLOYS, describes ways to avoid the loss of the amorphous structure and to exploit the microcrystalline structure, but as with other approaches to date these have several disadvantages and are expensive and difficult to carry out, especially for actual parts rather than test samples.
Even aluminum which is much softer than Ni based alloys can not be consolidated to form a part without loss of the desired amorphous or microcrystalline structure. U.S. Pat. No. 4,869,751, THERMOMECHANICAL PROCESSING OF RAPIDLY SOLIDIFIED HIGH TEMPERATURE Al-BASE ALLOYS, teaches how to retain some of the desired microstructure, but high temperatures, 400 to 500° C., (for aluminum) have to be used, so most of the potential properties are lost.
Hence, there is a need for an improved method to fabricate large, consolidated forms with amorphous metallic materials. The method should avoid the exposure of the amorphous material to high temperatures and should be economical. Additionally, there is a need for a method to control the microstructure of alloys during manufacturing and processing treatments. The present invention addresses one or more of these needs and others not explicitly or implicitly stated herein.